Add ServerConstants and its module to common

common/src/lib.rs

@@ -32,6 +32,7 @@ pub mod comp;
 pub mod consts;
 pub mod resources;
 pub mod uid;
+pub mod shared_server_config;
 
 // NOTE: Comment out macro to get rustfmt to re-order these as needed.
 cfg_if! { if #[cfg(not(target_arch = "wasm32"))] {

common/src/shared_server_config.rs

@@ -0,0 +1,4 @@
+/// Per-server constant data (configs) that stays the same for the server's life.
+pub struct ServerConstants {
+    day_cycle_coefficient: f64,
+}